81994508767 has 2 divisors, whose sum is σ = 81994508768. Its totient is φ = 81994508766.

The previous prime is 81994508663. The next prime is 81994508809. The reversal of 81994508767 is 76780549918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81994508767 - 2⁷ = 81994508639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81994508699 and 81994508708.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81994508567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40997254383 + 40997254384.

It is an arithmetic number, because the mean of its divisors is an integer number (40997254384).

Almost surely, 2^81994508767 is an apocalyptic number.

81994508767 is a deficient number, since it is larger than the sum of its proper divisors (1).

81994508767 is an equidigital number, since it uses as much as digits as its factorization.

81994508767 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30481920, while the sum is 64.

The spelling of 81994508767 in words is "eighty-one billion, nine hundred ninety-four million, five hundred eight thousand, seven hundred sixty-seven".